Casting sulphur



,Patente d A151. -14, 1925.

UNITED STATES I 1,533,213 PATENT OFFICE.

JAMES W'. SGHWAB, OF GULF, TEXAS, ASSIGNOR TO TEXAS .GULF SULPHUR COM- IPANY, F BAY CITY, TEXAS, A GORPQRATION OF TEXAS.

oAsrme SULPHUR.

1W0 Drawing.

To all-whom it may concern Be it known that I, JAMES W. SGHWAB, a citizen of the United States, residing at Gulf, in the county of Matagorda, State of Texas, have invented certain'new and useful Improvements in Casting Sulphur; and

I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to the solidification or casting of molten sulphur, and has for its object the provision of certain improvements in casting sulphur whereby the sulphur is rendered easily parted from the surface against which it solidifies.

In the production or mining of sulphur by underground fusion, for example, in accordance with the well known-Frasch proccess, a fusing fluid, such as superheated water, is conveyed to the underground sulphur deposit where its heat is utilized in fusing the sulphur and the fused sulphur is raised to the surface of the ground in a molten condition by suitable agencies, such as an air lift pump. v

The satisfactory disposition of the molten sulphur as it is discharged at the surface of the ground from the so-called sulphur wells presents certain peculiar difficulties. At the present time, it is the customary practice to solidify the sulphur in the form of a huge block or pilecontaining many thousands block or pile. In actual practice, many weeks and frequently months elapse before this block of sulphur becomes solid throughout its entire mass.

The block or pile of sulphur, formed as above described, must be broken up for the subsequent handling and shipment from the sulphur field to the consumer. To this end,

it is necessary to blast the sulphur pile in substantially the same manner that. rock is Application filed November 2, 1923. Serial No. 672,445.

blasted. By repeated blasting and considerable manual labor, the sulphur is-finally prepared .for loading, usually by automatic loading machinery, into freight cars or other conveyances of transportation. The present practice of solidifying the molten sulphur thus-involves the formation of a huge pile of solid sulphur and the subsequent breaking up of this pile of sulphur into suitable form for convenient'handling and transportation. The present practice in this-respect necessitates the provision above ground of an enormous quantity of sulphur since while one pile or block of $111- phur is being broken down and shipped, another block must be in process of formation, and on this account many thousands of tons of sulphur are constantly maintained above ground. This is obviously an uneconomical procedure and it is extremel desirable that a more rapid method of soli ifying sulphur be provided by which the molten sulphur maybe prepared for shipment within a relatively short time after it is discharged from the sulphur wells, thereby reducing the amount'of sulphur which must be accumulated above ground.

From an operating standpoint the most suitable rapid methods of solidification are those which cast the sulphur in relatively small cakes in a pan conveyor or in large cakes by building up such cakes in thin layers on a belt conveyor.

One of the greatest operating drawbacks to these methods of rapid solidification is the difliculty with which solid sulphur is freed from the mold or belt upon which it has solidified, Efforts have been made to overcome this tendency of the sulphur to cling to the surfaces against which it solidifies by the application of exterior means, such as moistening the inner surfaces of the mold with water or other liquids and at the same time allowing the mold to rest in water. Under proper conditions this results in such rapid cooling of a thin layer of sulphur next the sides and bottom of the mold that the water inside the mold is not evaporated by the heat from the sulphur but remains as a thin film and keeps the sulphur from adhering to the mold. But if the inner surface of the mold is not entirely wetted the sulphur comes into direct contact with the surface of the mold in that portion which is not wettcd I have discovered that sulphur may be ren and may stick to the mold. In many cases it clings so tenaciously to the molds that the solid cake must be laboriously broken out in small pieces by hand. If there is too much water in the mold some ofit may become enclosed in the solid sulphur and greatly increase the moisture content of the product.

In contradistinction to these efforts to overcome the tendency of sulphur to cling to the surfaces against which it solidifies,

--monia, for a sufiicient time to allow the alkaline substance to react with the sulphur, it may be readily and easilyremoved from the molds in which it is solidified or cast. Preferably, the thus treated sulphur should be cast as soon as possible after treatment.

In accordance with my preferred practice of the invention, 1 subject molten'sulphur to an appropriate preliminary treatment with ammonia whereby the ammonia is brought in intimate contact with the molten sulphur -fora sufficient time for the sulphunto take up the ammonia. The ammonia may be added to the sulphur in any convenient manner. In order to conserve ammonia it is best to agitate the liquid sulphur with the required amount of ammonia in a closed tank. A similar result may be obtained by other means such as circulating the ammonia through the liquid sulphur in a closed tank I by means of a pump or blower, or, if condltions permit, y simply bubbling the am- I monia through the liquid'sulphur in an open tank and allowing the excess ammonia to escape. The sulphur should be cast" as soon as possible after treatment.

,. The amount of ammonia required to bring about. the desired result varies somewhat with the sulphur. Good results may be obtained when treating Frasch process sulphur with from about 0.023 pound to about 0.09 pound of ammonia per long ton of sulphur. In some cases an even smaller amount of ammonia may be sufficient.

The duration of treatment or the period of contact between-the liquid sulphur and ammonia may vary somewhat with the quantity of sulphur being treated and the method employed. for bringing about the intimate contact between the sulphur and ammonia.

I have secured satisfactory results when art its ten ency to cling to the agitating the mixture of ammonia and sulphur ,for about one minute.

The temperature at which treatment and subsequent pouring into molds takes place J has little elfect upon the final result although the more nearly the sulphur approaches the temperature of;its solidification point and the cooler the mold, the more rapidly the solidification and parting from the mold. In actual practice the sulphurcan best be handled at the temperature ordinarily used for transporting liquid sulphur, namely, about 130-140 C. The length of time required for cooling the cast sulphur may be materially shortened by making use of any of the well known expedients for this purpose, such, for example, as allowing the outside surface of the mold to dip into water.

actual amount-of ammonia required and to show by comparison with untreated sulphur the greater rapidity with which ammonia treated sulphur parts from the mold. In 1 making the experiments small quantities of liquid ammonia were sealed inglass tubes and weighed. A tube containing a known weight of ammonia was dropped into a flask containing a weighed amount of liquid sulphur. The flash was quickly stoppered and shaken. The glass tube was broken by the great increase in pressure and the ammonia vaporized instantaneously. The flask containing this mixture of sulphur and vammonia was then shaken continuously for about one minute so that the sulphur and ammonia came into intimate contact. The sulphur was then poured into a mold and the time required for the sulphur to part 106 .from the mold noted. Glass molds werecasting untreated sulphur. 15

. Tempereturein Lbs. degrees Time 7 at R r on er emar P501101 During At rem sulphur treatppurmold ment mg 0.09 .122 122 No.- 20sec--- 0.075 148 138 N0---- 6min--- Mold heated to 140 C. at start. 1 25 0.045 140 120 No.... 15sec--- 0.038 148 136 N0 5min--. 0.03 145 {22 N0..- 2min 0. O3 146 30 NO 2.5 min 0. 03 146 132 Yes 1 min 0.023 145 N0' 2min. p.023 145 126 Yes" min...

Temperature in Lbs degrees C. ammonia Mold perlong Water Tune ttlino iigrt from ton of During At cooled sulphur treatpour ment mg None 140 No min. N n 121 No 18min. None 124 Yes 16min.

I claim:

1. The improvement in casting sulphur which comprises subjecting molten sulphur to a preliminary treatment with an alkaline substance for modifying the properties of the sulphur so as to eliminate in large part its tendency to cling to the surface of a mold, and thereafter casting in molds the sulphur thus treated.

2. The improvement in casting sulphur which comprises bringing molten sulphur in intimate contact with ammonia so as to modify the properties of the sulphur to eliminate in large part its tendency to cling to the surface of a mold, and thereafter casting the sulphur in molds.

3. The improvement in casting sulphur which comprises bringing molten sulphur in intimate contact with ammonia at a temperature slightly greater than the temperature of solidification of the sulphur so as to modify the properties of the sulphur to eliminate in large part its tendency to cling to the surface of a mold, and thereafter pouring the sulphur in molds ,for solidification.

In testimony whereof I aflix my signature.

JS w. SCHWAB. 

